Such heating apparatuses are used, e.g., in conjunction with lip rolling apparatuses in which blanked and deep-drawn plastic cups are provided with a rolled rim. To preheat the plastic cups to a specific prescribed temperature, they must pass through a heating section in which they are heated simultaneously on all sides. Consequently, the heating apparatus must be configured such that it encloses the cups. On the other hand, however, the cups also must be accessible if problems should arise in the cup transport through the heating apparatus and the cups must be removed from the heating apparatus manually. Multiple-part heating apparatuses allowing to be opened when needed suggest themselves for that purpose. Concerned in the simplest configuration are two heating boxes which enclose the object(s) to be heated and can be folded open for access to their interior.
In prior heating apparatuses, the heating boxes are merely moved apart, requiring the operating personnel to reach into the interior of the heating apparatus for removal of any jammed objects. Since the heating apparatus is mostly not turned off for such work, or is still hot, the operator may suffer burn wounds on the hot components.
A further disadvantage is constituted by the appreciable loss of energy that occurs when opening the heating apparatus. Once the heating apparatus is being closed again after repairs, it takes some time for the desired process temperature to restore.
The objective underlying the invention, therefore, is a heating apparatus which avoids the disadvantages of the prior art and guarantees, if needed, nonproblematic access to the objects to be heated, without incurring any heat losses. The foregoing objective is met by the provision of a heating apparatus which utilizes at least two heating chambers having open sides which face each other so as to close the chambers. The chambers are so arranged relative to each other in a first operating position and in a second inoperative position. The first and second positions are 180.degree. apart (eg. front and back). The chambers are mounted so as to enable them to be swung in an arc in opposite directions from the first to second positions.
The design of the heating apparatus is such that the heating boxes are able to swing about, such that in their inoperative position away from the object they are in closed position as well. With the heating apparatus closed also in its inoperative position, no energy losses whatsoever occur during the operator's work. Besides, the heating apparatus is located then a specified distance from the object, so that the operating personnel will in such work make no contact at all with the heating apparatus.
The heating boxes are preferably of a superjacent arrangement, their open sides facing each other. Each heating box is on its two end walls preferably joined, in a fashion allowing swing movement, to a stationary support assembly by way of a parallelogram linkage. A parallelogram linkage offers the advantage that the heating boxes retain their position relative to each other when being swung, making it possible to move them, in their inoperative position, to a position corresponding to the working position. Both heating boxes move between inoperative and working position along a circular arc, with the top box swinging upward and the bottom box swinging down. The heating boxes can thereby transform from one closed position to another closed position. The heating boxes retract at the same time from the object being heated.
The support element features preferably a drive system which hinges to the points of articulation of the parallelogram linkage on the support assembly. Arranged in said points of articulation are preferably gears which are engaged by a cogged belt or a respective drive means connecting to a motor.
Exemplary embodiments of the invention are more fully described hereafter with the aid of the drawings, which show in: